Decoupling Infill Walls to Match Floor Stiffness

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Solution Overview

Problem

Soft story buildings are vulnerable to collapse under lateral loading conditions, such as earthquakes, due to inadequate stiffness, leading to disproportionate lateral stress and potential structural failure, as seen in events like the Loma Prieta earthquake, where such buildings suffered significant damage and destruction.

Innovation Solution

The method involves decoupling the structural frame from infill walls in upper floors to reduce in-plane interaction, using connectors with slots that allow relative horizontal and vertical movements, thereby matching the stiffness of upper floors to the ground floor, eliminating the soft story phenomenon while maintaining architectural functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the structural stiffness of upper floors is increased to resist lateral loads, then the building's resistance to lateral motion improves, but the soft story vulnerability worsens due to disproportionate drift concentration

Engineering Contradiction:

Improveresistance to lateral loadsVSAvoidsoft story collapse resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the stiffness parameter of the upper floors by decoupling infill walls from the structural frame, transforming the upper floors from a stiff condition to a more flexible condition that matches the ground floor stiffness, thereby eliminating the soft story effect

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent extracts the infill walls from the structural system by decoupling them from the structural frame, removing their contribution to in-plane stiffness and allowing the structural frame to behave independently with reduced stiffness

Inventive Principle:

Principle #2Taking out (Extraction)

2Strength

If braces are added to the soft story to increase rigidity, then lateral load resistance improves, but architectural functionality deteriorates due to limited open floor space

Engineering Contradiction:

Improvesoft story rigidityVSAvoidarchitectural function

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

Instead of the conventional approach of increasing ground floor stiffness through braces or reinforcement, the patent inverts the solution by decreasing upper floor stiffness to match the ground floor, achieving the same stability goal without compromising architectural space

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If structural members are enlarged to create a reinforced soft story, then collapse resistance improves, but device complexity increases

Engineering Contradiction:

Improvecollapse resistanceVSAvoidstructural member size

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the stiffness parameter through connection details (decoupling infill walls) rather than changing the size or geometry of structural members, achieving the desired stiffness match without increasing structural complexity

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12180696B1Systems and methods for resisting soft story collapse

Publication Date: 2024.12.31 THE STEEL NETWORK

AI summary

The present subject matter relates to systems and methods for providing resistance to soft story collapse in a multi-story structure. Such systems and methods includes providing a multi-story structure having a first floor and one or more upper floors, wherein a structural of the first floor is less than 70% of a structural stiffness of the one or more upper floors, and decreasing the structural stiffness of the one or more upper floors to be less than or substantially equal to the structural stiffness of the first floor.